If any two improvements have dramatically improved vehicular safety for vehicle occupants, those two improvements are the seatbelt and the airbag. As provision and use of these two important safety devices has increased, automotive and vehicular safety has improved dramatically. At the same time, both of these safety devices have disadvantages--with the airbag's faults being the most serious of the two.
Traditional airbags are detonated by crash sensors, and sudden airbag inflation is caused by gas generation--typically sodium azide, sodium hydroxide or carbon dioxide gas delivered from strategically positioned canisters. Thus the traditional airbag propels toward the driver or the passenger, on the wave of an exploding gas, and immobilizes the driver or passenger for a brief period. Although the potential contusion and noise/ear damage risks are appreciated in a general way by the public, usually only health care providers see the serious injury airbag deployment can cause. And while relatively lesser injury is certainly preferable to life-threatening injury or death, any injuries caused by so-called "safety" devices should be avoided if at all possible.
For example, clinicians have documented instances in which a driver or passenger smoking a pipe has been impaled through the back of the throat with the pipe stem upon airbag inflation. Similar injuries are sustained by passengers who may be eating or working while riding--any pens, pencils or dining implements (even plastic ones) in the vicinity of the head pose injury risks, especially considering the widespread unconscious habit of chewing on the end of a writing implement. An even greater injury risk is the wearing of ordinary eyeglasses: the surgical removal of eyeglasses embedded around a driver's or passenger's eyes after airbag inflation is already documented in the medical literature, and clearly head injuries of this kind should be avoided if there is any way to do so.
A further disadvantage with traditional airbags has to do with their directionality. A typical, steering-column driver's side airbag can protect a driver from a head-on vehicular impact, but offers little or no protection in a side collision, particularly to the driver's left. Likewise, a passenger-side airbag offers little or no protection to the passenger's right side. Automobile manufacturers are at this writing beginning to introduce side airbags in an effort to address this problem, but the costs involved in this approach are prohibitive. For one thing, side airbags do not replace front airbags and the provision of both therefore at least doubles the cost of providing a single airbag. Also, door designs have not to date lent themselves to airbag incorporation, so that side air bags have required door redesigns which increase costs even further.
Even seatbelts are known to have been plagued with unique problems. A traditional seatbelt can cause its own contusion depending on the force of impact, and while most of these contusions lead only to bruises, more serious damage has also occurred. It is known from the literature to provide for localized inflation to a seat belt, upon vehicle impact, to provide a cushion between the belt and the individual wearing it, but this design has not been widely adopted. A goal of improved vehicular restraint technology thus includes the elimination of seatbelt contusions resulting from vehicle impact.
In view of all of the above, a need remains for a vehicular restraint system in which the benefits of seatbelts and airbags are preserved but the injury caused by the impact of the seatbelt and/or the airbag is minimized or avoided.